The Revenge of Chicken Pox

Vaccines work. That is a very solid scientific conclusion based upon decades of evidence involving hundreds of millions of people. But no scientific conclusion is so rock solid that there aren’t those who will deny it. The human capacity for self-deception appears to be limitless.

But for those who are not already too far down the rabbit hole, who may just be poorly informed or misinformed, occasional reminders of what should be obvious are helpful. The thing about vaccines – if you refuse to use them based upon misinformation about their efficacy, or baseless fears about their safety, there will be a highly predictable result. Vaccines prevent communicable diseases, and where there are pockets of people refusing vaccines, those diseases will come back with a vengeance.

Chickenpox used to be very common in the United States. In the early 1990s, an average of 4 million people got varicella, 10,500 to 13,000 were hospitalized (range, 8,000 to 18,000), and 100 to 150 died each year. In the 1990s, the highest rate of varicella was reported in preschool-aged children.

And:

Varicella incidence, based on national passive surveillance data published in 2012, declined 79% during 2000-2010 in 31 states that met CDC’s criteria for adequate and consistent reporting. From this same data source, incidence declined 72% during 2006-2010, after a routine second dose of varicella vaccine was recommended. Varicella incidence from 2 active surveillance sites declined 98% during 1995-2010.

This is similar to what has happened after the introduction of every major vaccination program – the incidence of the targeted disease plummeted. Antivaxxers argue, implausibly, that this is just a coincidence. The incidence was dropping anyway. Sometimes they improperly use death rates rather than incidence rates, the former reflecting the overall quality of health care and not just the spread of the disease.

But this claim is simply absurd. The correlation between the introduction of vaccines and the precipitous decline in disease incidence is overwhelming. Chickenpox is just the latest example.

Further – when you take the vaccine away, the disease comes back. We are increasingly seeing infectious disease outbreaks in areas with high vaccine refusal. Unvaccinated children tend to cluster in schools that are permissive about vaccine avoidance. They then create an environment in which an outbreak can occur. This, then, threatens the broader community, and frustrates efforts at elimination.

Even though the data is absolutely clear, antivaxxers are so dedicated to their narrative that facts don’t matter. That narrative, however, has to be criticized, exposed, and marginalized, because it is an active danger to the health of society.

I know this message is like a broken record on SBM, but that is part of what we do – serve as a persistent reminder that facts matter, science matters, and you ignore reality at your own peril – and in the case of vaccines, at society’s peril.

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.